build and upload executables created by PyInstaller

- create release on tag push
- build executables by PyInstaller:
    - extract_otp_secrets_linux_x86_64 (glibc 2.28)
    - extract_otp_secrets_win_x86_64.exe
    - extract_otp_secrets_macos_x86_64 (untested)
- add --version
- build linux executable in docker container
- update README
    - add TOC
    - improve badges
    - add PyInstaller section
- docker
    - build BASE_IMAGE as ARG
    - copy only required files to image
    - add .alias
- build.sh
    - fix clean
    - fix generate results
    - generate TOC

run_pytest.sh

@@ -1,3 +1,5 @@
 #!/bin/sh
 cd /extract
-pip install -U pytest pytest-mock && pip install --no-deps . && pytest "$@"
+mkdir -p tests
+ln -sf /extract/data tests/data
+pip install -U pytest pytest-mock && pytest "$@"